HMOX1 and Parkinson disease: While Aβ levels faced controversial results, the p-tau/t-tau ratio was found to significantly increase in AD patients; oligomeric α-synuclein/total α-synuclein could be important in defining PD progression; heme-oxygenase-1 (HO-1) and AChE activity were reported to be increased in PD patients’ saliva and therefore are possible candidates as biomarkers for PD; lactoferrin, an antimicrobial peptide showing similar binding properties to Aβ, was also suggested as a salivary biomarker as it has been detected in plaques, NFTs and microglia of AD patients’ brains.